The present invention relates to floatable vessels, and more particularly to a hull construction for improving the wave-response behavior of a floating barge.
Offshore activities, especially those connected with the discovery and recovery of crude oil, are often conducted from floating vessels, such as pipe-laying barges, pipe-burying barges, derrick barges, drill barges, and numerous other forms of support barges and ships. Many of these vessels are characterized by high statical stability due to a relatively large metacentric height, thus making them highly resistant to capsizing.
On the other hand, features which typically establish high statical stability are generally responsible for low dynamic stability, meaning that the vessels are highly responsive to wave motion. In relatively calm waters, low dynamic stability can be tolerated. However, oil-related activities are presently being conducted in regions where severely rough wave conditions are prevalent, such as in the North Sea, where low dynamic stability presents serious drawbacks.
Vessels of high static stability can operate in such rough sea regions with minimal likelihood of capsizing. However, the low dynamic stability of these vessels results in severe ship motion, especially in roll and heave, which can hamper or prevent the conductance of normal onboard activities during rough sea conditions.
It is, therefore, an object of the present invention to minimize or obviate problems of this sort.
It is another object of the invention to provide a floatable vessel whose dynamic and statical stability permit satisfactory barge operation in both calm and rough seas.
It is yet a further object of the invention to provide such a vessel whose metacentric height can be adjustably regulated.
It is still another object of the invention to provide a vessel which exhibits a high resistance to capsizing as well as a considerably long natural period of roll.
It is a further object of the invention to provide such a vessel whose overall dimensions are not unlike that of a conventional barge and yet which is characterized by longitudinally troughed sides, and buoyancy equipment above and below water level for selectively altering the metacentric height of the vessel.
It is still another object of the invention to provide a unique method for modifying a conventional vessel in accordance with the previously outlined objects, as well as a novel method for operating such a barge to regulate the metacentric height.